<!DOCTYPE html>
<html class="ui-page-login">

<head>


</head>


<body>
<script type="text/javascript">
    let s1 = Symbol.for("foo");
    console.log(Symbol.keyFor(s1)) // "foo"

    let s2 = Symbol("foo");
    console.log(Symbol.keyFor(s2)) // undefined




</script>

</body>

</html>